506725-01
Page 18 of 48
Issue 1109
Intake Piping
This furnace may be installed in either
direct vent
or
non-
direct vent
applications. In non-direct vent applications,
when intake air will be drawn into the furnace from the
surrounding space, the indoor air quality must be considered.
Guidelines listed in Combustion, Dilution and Ventilation Air
section must be followed.
Follow the next two steps when installing the unit in
Direct
Vent applications
, where combustion air is taken from
outdoors and flue gases are discharged outdoors.
The
provided air intake screen must not be used in direct
vent applications (outdoors).
1. Use cement or a sheet metal screw to secure the intake
pipe to the inlet air connector.
2. Route piping to outside of structure. Continue with
installation following instructions given in general guide
lines for piping terminations and intake and exhaust
piping terminations for direct vent sections. Refer to
Table 7 for pipe sizes.
Follow the next two steps when installing the unit in
Non-Direct Vent applications
where combustion air is
taken from indoors and flue gases are discharged outdoors.
1. Use field-provided materials and the factory-provided
air intake screen to route the intake piping as shown in
Figure 23. Maintain a minimum clearance of 3" (76 mm)
around the air intake opening. The air intake opening
(with the protective screen) should always be directed
forward, or sideways.
2. Use a sheet metal screw to secure the intake pipe to
the connector, if desired.
General Guidelines for Vent Terminations
In Non-Direct Vent applications, combustion air is taken from
indoors and the flue gases are discharged to the outdoors.
This unit is then classified as a non-direct vent, Category IV
gas furnace.
In Direct Vent applications, combustion air is taken from
outdoors and the flue gases are discharged to the outdoors.
This unit is then classified as a direct vent, Category IV gas
furnace.
In both Non-Direct Vent and Direct Vent applications, the
vent termination is limited by local building codes. In the
absence of local codes, refer to the current National Fuel
Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current CSA-
B149 Natural Gas and Propane Installation Codes in Canada
for details.
Position termination according to location given in Figure 23
or 24. In addition, position termination so it is free from any
obstructions and 12" above the average snow accumulation.
At vent termination, care must be taken to maintain protective
coatings over building materials (prolonged exposure to
exhaust condensate can destroy protective coatings). It is
recommended that the exhaust outlet not be located within
6 feet (1.8 m) of a condensing unit because the condensate
can damage the painted coating.
NOTE:
If winter design temperature is below 32° F (0° C), it is
recommended that the exhaust piping be insulated with
1/2"
(13
mm), Armaflex or equivalent when run through an unconditioned
area. In extremely cold climate areas with temperature below 20°
F (6.7° C) it is recommended that
3/4"
(19 mm) Armaflex or
equivalent be used. Insulation on outside runs of exhaust pipe
may be painted or wrapped
to
protect insulation from deterioration
in accordance with the insulation manufacturers recommendation.
Exhaust pipe insulation may not be necessary in some specific
applications.
NOTE:
During extremely cold temperatures, below approximately
20° F
(6°
C), units with long runs of vent pipe through unconditioned
space, even when insulated, may form ice in the exhaust
termination that prevents the unit from operating properly. Longer
run times of
at
least 5 minutes will alleviate most icing problems.
Also,
a
heating cable may be installed on exhaust piping and
termination
to
prevent freeze-ups. Heating cable installation kits
are available, see unit specification sheets for part numbers.
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze-ups and may
block the terminations.
IMPORTANT
For Canadian Installations Only:
In accordance to CSA International B149 installation
codes, the minimum allowed distance between the
combustion air intake inlet and the exhaust outlet of
other appliances shall not be less than 12 inches (305
mm).
IMPORTANT
FIGURE 22
TYPICAL AIR
INTAKE
PIPE CONNECTIONS
NON−DIRECT VENT APPLICATIONS
AIR
INTAKE
SCREEN
(Provided)
NOTE:
Air intake screen and elbow may be rotated, so that
screen may be positioned to face forward or to either side.
